Compounds of Formula (I): are structurally novel antiepileptic compounds that are highly effective anticonvulsants in animal tests (MARYANOFF, B. E, NORTEY, S. O., GARDOCKI, J. F., SHANK, R. P. AND DODGSON, S. P. J. Med. Chem. 1987, 30, 880-887; MARYANOFF, B. E., COSTANZO, M. J., SHANK, R. P., SCHUPSKY, J. J., ORTEGON, M. E., AND VAUGHT J. L. Bioorg. Med. Chem. Lett 1993, 3, 2653-2656; SHANK, R. P., GARDOCKI, J. F., VAUGHT, J. L., DAVIS, C. B., SCHUPSKY, J. J., RAFFA, R. B., DODGSON, S. J., NORTEY, S. O., MARYANOFF, B. E. Epilepsia 1994, 35, 450-460; MARYANOFF B E, COSTANZO M J, NORTEY S O, GRECO M N, SHANK R P, SCHUPSKY J J, ORTEGON M P, VAUGHT J L. J. Med. Chem. 1998, 41, 1315-1343). These compounds are covered by three U.S. Pat. Nos. 4,513,006, 5,242,942, and 5,384,327. One of these compounds 2,3:4,5-bis-O-(1-methylethylidene)-β-D-fructopyranose sulfamate known as topiramate has been demonstrated in clinical trials of human epilepsy to be effective as adjunctive therapy or as monotherapy in treating simple and complex partial seizures and secondarily generalized seizures (E. FAUGHT, B. J. WILDER, R. E. RAMSEY, R. A. REIFE, L D. KRAMER, G. W. PLEDGER, R. M. KARIM et. al., Epilepsia 1995, 36 (S4), 33; S. K. SACHDEO, R. C. SACHDEO, R. A. REIFE, P. LIM and G. PLEDGER, Epilepsia 1995, 36 (S4), 33; T. A. GLAUSER, Epilepsia 1999, 40 (S5), S71-80; R. C. SACHDEO, Clin. Pharmacokinet. 1998, 34, 335-346), and is currently marketed for the treatment of seizures in patients with simple and complex partial epilepsy and seizures in patients with primary or secondary generalized seizures in the United States, Europe and most other markets throughout the world.
Compounds of Formula (I) were initially found to possess anticonvulsant activity in the traditional maximal electroshock seizure (MES) test in mice (SHANK, R. P., GARDOCKI, J. F., VAUGHT, J. L., DAVIS, C. B., SCHUPSKY, J. J., RAFFA, R. B., DODGSON, S. J., NORTEY, S. O., and MARYANOFF, B. E., Epilepsia 1994, 35, 450-460). Subsequent studies revealed that Compounds of Formula (I) were also highly effective in the MES test in rats. Topiramate was also found to effectively block seizures in several rodent models of epilepsy (J. NAKAMURA, S. TAMURA, T. KANDA, A. ISHII, K. ISHIHARA, T. SERIKAWA, J. YAMADA, and M. SASA, Eur. J. Pharmacol. 1994, 254, 83-89), and in an animal model of kindled epilepsy (A. WAUQUIER and S. ZHOU, Epilepsy Res. 1996, 24, 73-77).
More recently compounds of formula (I) have been found to be effective for maintaining weight loss, as disclosed in WIPO publication WO/0061140, for the treatment of obesity, as disclosed in U.S. Pat. No. 6,071,537 (WO 9800130), for lowering blood glucose levels, as disclosed in WIPO publication WO00/61139 and for lowering lipids as disclosed in WIPO publication WO00/61137. Thakur et al in WIPO publication WO99/44581 disclose the use of topiramate for the treatment of diabetes.
Type II diabetes mellitus (non-insulin-dependent diabetes mellitus or NIDDM) is a metabolic disorder involving dysregulation of glucose metabolism and insulin resistance, and long-term complications involving the eyes, kidneys, nerves, and blood vessels. Type II diabetes mellitus usually develops in adulthood (middle life or later) and is described as the body's inability to make either sufficient insulin (abnormal insulin secretion) or its inability to effectively use insulin (resistance to insulin action in target organs and tissues). More particularly, patients suffering from Type II diabetes mellitus have a relative insulin deficiency. That is, in these patients, plasma insulin levels are normal to high in absolute terms, although they are lower than predicted for the level of plasma glucose that is present.
Type II diabetes mellitus is characterized by the following clinical signs or symptoms: persistently elevated plasma glucose concentration or hyperglycemia; polyuria; polydipsia and/or polyphagia; chronic microvascular complications such as retinopathy, nephropathy and neuropathy; and macrovascular complications such as hyperlipidemia and hypertension which can lead to blindness, end-stage renal disease, limb amputation and myocardial infarction.
Syndrome X, also termed Insulin Resistance Syndrome (IRS), Metabolic Syndrome, or Metabolic Syndrome X, is a disorder that presents risk factors for the development of Type II diabetes mellitus and cardiovascular disease including glucose intolerance, hyperinsulinemia and insulin resistance, hypertriglyceridemia, hypertension and obesity.
The diagnosis of Type II diabetes mellitus includes assessment of symptoms and measurement of glucose in the urine and blood. Blood glucose level determination is necessary for an accurate diagnosis. More specifically, fasting blood glucose level determination is a standard approach used. However, the oral glucose tolerance test (OGTT) is considered to be more sensitive than fasted blood glucose level. Type II diabetes mellitus is associated with impaired oral glucose tolerance (OGT). The OGTT thus can aid in the diagnosis of Type II diabetes mellitus, although generally not necessary for the diagnosis of diabetes (Emancipator K, Am J Clin Pathol 1999 Nov;112(5):665-74; Type 2 Diabetes Mellitus, Decision Resources Inc., March 2000). The OGTT allows for an estimation of pancreatic beta-cell secretory function and insulin sensitivity, which helps in the diagnosis of Type II diabetes mellitus and evaluation of the severity or progression of the disease (e.g., Caumo A, Bergman R N, Cobelli C,. J Clin Endocrinol Metab 2000, 85(11):4396-402). More particularly, the OGTT is extremely helpful in establishing the degree of hyperglycemia in patients with multiple borderline fasting blood glucose levels that have not been diagnosed as diabetics. In addition, the OGTT is useful in testing patients with symptoms of Type II diabetes mellitus where the possible diagnosis of abnormal carbohydrate metabolism has to be clearly established or refuted.
Thus, impaired glucose tolerance is diagnosed in individuals that have fasting blood glucose levels less than those required for a diagnosis of Type II diabetes mellitus, but have a plasma glucose response during the OGTT between normal and diabetics. Impaired glucose tolerance is considered a prediabetic condition, and impaired glucose tolerance (as defined by the OGTT) is a strong predictor for the development of Type II diabetes mellitus (Haffner S M, Diabet Med 1997 Aug;14 Suppl 3:S12-8).
Type II diabetes mellitus is a progressive disease associated with the reduction of pancreatic function and/or other insulin-related processes, aggravated by increased plasma glucose levels. Thus, Type II diabetes mellitus usually has a prolonged prediabetic phase and various pathophysiological mechanisms can lead to pathological hyperglycemia and impaired glucose tolerance, for instance, abnormalities in glucose utilization and effectiveness, insulin action and/or insulin production in the prediabetic state (Goldberg R B, Med Clin North Am 1998 Jul; 82(4):805-21).
The prediabetic state associated with glucose intolerance can also be associated with a predisposition to abdominal obesity, insulin resistance, hyperlipidemia, and high blood pressure, that is, Syndrome X (Groop L, Forsblom C, Lehtovirta M, Am J Hypertens 1997 Sep;10(9 Pt 2):172S-180S; Haffner S M, J Diabetes Complications 1997 Mar-Apr;11(2):69-76; Beck-Nielsen H, Henriksen J E, Alford F, Hother-Nielson O, Diabet Med 1996 Sep;13(9 Suppl 6):S78-84).
Thus, defective carbohydrate metabolism is pivotal to the pathogenesis of Type II diabetes mellitus and impaired glucose tolerance (Dinneen S F, Diabet Med 1997 Aug;14 Suppl 3:S19-24). In fact, a continuum from impaired glucose tolerance and impaired fasting glucose to definitive Type II diabetes mellitus exists (Ramlo-Halsted B A, Edelman S V, Prim Care 1999 Dec;26(4):771-89).
Early intervention in individuals at risk to develop Type II diabetes mellitus, focusing on reducing the pathological hyperglycemia or impaired glucose tolerance may prevent or delay the progression towards Type II diabetes mellitus and associated complications and/or Syndrome X. Therefore, by effectively treating impaired oral glucose tolerance and/or elevated blood glucose levels, one can prevent or inhibit the progression of the disorder to Type II diabetes mellitus or Syndrome X.
Many anti-diabetic agents typically prescribed for the treatment of Type II diabetes mellitus and/or Syndrome X, for example, sulfonylureas and thiazolidinediones, have an undesired side effect of increasing body weight. Increased body weight in patients with prediabetic conditions or with diagnosed Type II diabetes mellitus or Syndrome X results in deleterious effects due to accentuation of the metabolic and endocrine dysregulation, and obesity per se is a pivotal risk factor for the development and progressive worsening of Type II diabetes mellitus. Thus it is desirable to have an anti-diabetic agent which maintains or lowers body weight.